Running air con with the windows open

[Actin]

Is a big no-no due to it messing up the air con thermostat isn't it? I've accidently opened the window once or twice.

How long does it take before damage is done? Also what temp should the air be at when its set to the coldest setting with the a/c running?

[andyman7931]

never ever heard this. If you run with the AC on you're just wasting energy...

[tastade]

I do it sometimes because I like my windows down, but I don't want to cook either. I have never had it hurt anything, my AC is as cold as ever. I usually just do this for a few minutes until the car cools off a bit and then I turn off the AC or roll up the windows. What I do more often though is run the heater in the winter with the windows down.

[Tyler]

Nothing will happen by doing this.

[campaiar]

A vehicle air conditioner ideally should output around 35-36 degrees at the vents with re-circ on.

Given that your car is 7-11 years old, its probably lost a step.

[bmw318tiChic]

I've never heard of any problems with driving with the AC on and windows open... I'm the same as "tastade".... so often I'll just ride with the windows down and heater on in the winter!

[DustenT]

Originally Posted by Actin

Is a big no-no due to it messing up the air con thermostat isn't it? I've accidently opened the window once or twice.

How long does it take before damage is done? Also what temp should the air be at when its set to the coldest setting with the a/c running?

It doesn't matter. The AC is a sealed unit, air is simply blown over the exchanger to make cold air. Now if your interior was filled with compressed freon.....that would be a problem.

[andyman7931]

Originally Posted by DustenT

It doesn't matter. The AC is a sealed unit, air is simply blown over the exchanger to make cold air. Now if your interior was filled with compressed freon.....that would be a problem.

if that's the case, you'd have bigger problems than your ac not working well!

[Tyler]

Originally Posted by campaiar

A vehicle air conditioner ideally should output around 35-36 degrees at the vents with re-circ on.

Given that your car is 7-11 years old, its probably lost a step.

Actually the air coming out of the vent should be inbetween 65-68 degrees,thats with the heat control turned all the way counter clockwise.. If your a/c is putting air out at 35-36 degrees your cars a/c has serious problems. Thats 5 degrees above freezing. Even new cars don't go that low. You want to use the re circ once the temp in the car is cool then it will just re circ the air inside. My car still puts out about 66 degrees.

[Severian]

Originally Posted by Tyler

Nothing will happen by doing this.

Actually, not true for some cars. Apparently not ours, but for my '99 mazda protege ES...

Campaign Number: 00V301000 Date: 2000-Oct-05
Component: Equipment: Electrical: Radio/tape Deck/cd Etc.

Defect Summary: VEHICLE DESCRIPTION: PASSENGER VEHICLES EQUIPPED WITH A PARTICULAR FACTORY INSTALLED AUDIO UNIT. IF THE VEHICLE IS OPERATED AT LOW SPEED IN A HOT AND HUMID ENVIRONMENT WITH THE WINDOW OPEN, AIR CONDITIONER RUNNING, AND AUDIO ON, CONDENSED WATER ON THE A/C DUCT SURFACE COULD DROP AND ENTER INTO THE AUDIO UNIT, CAUSING A SHORT CIRCUIT.

Consequence Summary: IF THE SHORT CIRCUIT OCCURS AT ONE SPECIFIC SET OF TERMINALS, THE REAR RIGHT LOUDSPEAKER CAN OVERHEAT AND, IN SOME CASES, CATCH FIRE.

[andyman7931]

but that's not damage to the AC unit... that's a poorly designed condensation system causing damage to something else...

[mrnine]

Wow...way to go Mazda. I can't imagine that BMW would build a car that if you accidentally ran your ac and your stereo with your windows down, your rear speaker could catch on fire. I can't help but giggle as I type it just thinking about it. That's perhaps the most ridiculous design flaw I've ever heard of.

[Actin]

^^^ sure is a crazy design flaw lol.

Anyway great info as always folks thanks!

[tastade]

Originally Posted by Tyler

Actually the air coming out of the vent should be inbetween 65-68 degrees,thats with the heat control turned all the way counter clockwise.. If your a/c is putting air out at 35-36 degrees your cars a/c has serious problems. Thats 5 degrees above freezing. Even new cars don't go that low. You want to use the re circ once the temp in the car is cool then it will just re circ the air inside. My car still puts out about 66 degrees.

Note that condensors in AC units do ice over on occassion (usually from a problem). It wouldn't surprise me if the air could get down to 35 degrees, I know my hands go numb if I point the vent at my hand on the steering wheel. Now I am going to have to go home and measure my as temp after work. But I am guessing mine get down around 40 or 50 F.

I had an old 300zx where the condensor would ice over after an hour of operation and the AC would stop working. I would turn it off for 10 minutes and it would be good for another hour. This only happened in very hot and humid climates.

This is also what causes that pool of water under your car when you stop after your AC has been running (condensation running off). I hate it when I am at a gas station and someone goes "look, your car is leaking fuel!" Then I have to explain to them that it is condensation from the AC. At least they are trying to be helpful.

[Severian]

Originally Posted by andyman7931

but that's not damage to the AC unit... that's a poorly designed condensation system causing damage to something else...

You seem to have missed the point of the humor in my post. However I should have been more clear that I was not being argumentative.